With the extreme cold and snow cover in many parts of the country this past winter, many farmers wonder about the weather's impact on disease and weed pressures in the upcoming planting and growing season.
"We do not know how the year will unfold for soybean farmers, but in any case, farmers should be aware of potential yield-robbing diseases and weeds and be prepared to take action," said Shawn Conley, Wisconsin State Soybean and Wheat Extension specialist.
Seedling diseases caused by Pythium, Phytophthora, Phomopsis and Rhizoctonia can be problems immediately. Early-season issues can include seed rots or seedling mortality (damping-off). Conditions that favor the development of early-season seedling issues include wet soil conditions at planting, slow germination and/or slow growth of seedlings, and poor seed quality. Early-season infection can also have a long latent period with symptoms not showing up until reproductive periods (for example, Phytophthoraor "root rot" as most farmers know it).
"Prevention management includes the use of high-quality soybean seed, fungicide seed treatments and resistant varieties," Conley said.
A well-designed weed management plan can be essential in maximizing soybean yields.
"Effective weed control can be vital in minimizing the negative effects from competition for light, water and other essential elements for plants," Conley said. "Reduced weed competition maximizes early-season crop growth rate, which quickens the time to full canopy closure and in turn maximizes intercepted light converted to soybean yield."
An effective weed management plan should include:
·Scouting reports that identifies target weed species so control efforts can be appropriately focused.
·Effective weed control preplanting so soybean seeds have a weed-free seedbed.
·Herbicides, with residual weed control activity, increases the flexibility for the proper timing of postemergence applications. This reduces the number of weeds exposed to postemergence herbicides and reduces the variability in the size of weeds at post-emergence spray timings.
·Rotate herbicide modes of action and tank-mix combinations to delay the increase of weed species that are difficult to control with specific herbicides and delay herbicide resistance.
For specific information on scouting fields for Sudden Death Syndrome, Brown Stem Rot, Soybean cyst nematode and others, check out the Wisconsin Soybean pocket guide available at coolbean.info/library/documents/WI_Soybean_Pocket_Guide.pdf. The pocket guide is made possible in part through checkoff funds of the Wisconsin Soybean Marketing Board.
In addition, Conley provides regular updates on soybean information. Visit www.coolbean.info throughout the growing season for the latest information on soybean issues.